Underwater removal of wooden piles has always been a difficult problem in waterfront maintenance and clearance projects. Typical pile removal methods are time consuming, hazardous, and often require large support equipment. Removal of wooden piles from waterfront structures during demolition or repair is normally accomplished by one of two methods. The first method is to remove the pile by pulling on it with a heavy crane. This is done by either using the crane to extract the pile completely, or pulling the pile from side-to-side until it breaks off at the mud line. This method limits the operation to work locations accessible by crane.
The second method is to physically cut the pile off at the mud line. Blasting, sawing, and shearing are common techniques used for cutting.
Shear type cutters typically operate by sliding two blades together in either a sliding guillotine motion or scissors type motion. The shear type cutter has several distinct advantages over blasting or the chain and reciprocating saws: since there are no high speed rotating or reciprocating blades, the shear type cutter is safer to operate.
A number of devices have been patented which relate to the problem of cutting elongated devices such as trees or piles in underwater environments. For example, U.S. Pat. No. 3,667,515, issued to Corey, discloses an apparatus that has a base with a guide adapted for receiving a pile, the base being adapted for reciprocal movement with respect to the pile, connectors affixed to the base for suspending the base in a substantially horizontal plane, a blade having a pair of opposite extremities, one of the extremities being pivotably mounted to the base, an actuator having a fixed member and a movable member, the fixed member being pivoted to the base and the movable member being pivotably mounted to the other extremity of the blade, the blade being swept across the guide when the actuator is engaged and being retracted away from the guide when the actuator is disengaged. When the pile cutter is lowered to the base of a pile, the guide being positioned about the pile for restricting the lateral movement of the base with respect to the pile, the actuator is engaged causing the blade to shear the pile at its base.
U.S. Pat. No. 2,707,008, entitled “Tree-Handling Method And Airborne Apparatus,” issued to Bannister, provides a gear-driven, cable operated device for cutting trees in remote locations. U.S. Pat. No. 3,056,267, issued to McRee, discloses of a dragline operated device and a method for removing from submerged sites portions of piles previously driven at their lower end into the water bed and having cap ends exposed above the water line. A frame is used that can be laterally shifted to a position poised above the pile with an opening through the frame in alignment with the cap of the pile. The frame is then lowered, making the frame captive to the pile. The frame is then guided to the mud line and the pile is severed at the mud line.
A forest harvester is the subject of U.S. Pat. No. 3,638,693. The machine described in that patent is intended for separating standing trees. The apparatus is a wheeled A-frame type device that supports an open-ended gripping member.
In U.S. Pat. No. RE 31,481, an apparatus is disclosed having an elongated frame including tree clamping jaws supported at one end and a shear-type cutting blade supported from the frame for movement therealong between an inactive position remote from the jaws and an active position cooperative with the jaws to shear a tree member clampingly engaged by the jaws.
A grab-type tree harvester is the subject of U.S. Pat. No. 4,537,236, which discloses the use of a pair of open-ended jaws to clamp the tree. A frame is connected to a lifting means through a rotating means in a manner such that the frame is adapted to rotate about a substantially vertical axis. The frame comprises grab means which are selectively moved by actuation means to an opened or closed position. Roller means for pulling a felled tree through the grab means is provided and at least one means for pruning a felled tree is also disclosed.
A hydraulically operated device for cutting trees, logs and the like is the subject of U.S. Pat. No. 3,270,787. That apparatus shows a hydraulic linked arm supported by a tractor with a pair of open-ended jaws at the distal end of the linkage.
While the devices identified above, and other devices in the prior art, work adequately to cut piles or trees at or above the bottom of a body of water, many water quality regulations now require that wooden piles be removed from at least the first two feet below the bottom of the water body. This is generally accomplished by removing the mud and silt from around the pile with some type of suction device and cutting the pile with a chain saw. Generally, the use suction device causes a significant increase in the turbidity of the water around the pile by stirring up the loose silt on the bottom, and the use of a chain saw causes saw dust particles to be released in the water body. Additionally, the material removed from around the pile is often contaminated with industrial chemicals and it either must be decontaminated before disposal or disposed in a facility licensed to accept contaminated material. For the purpose of this application, the bottom surface of any body of water will be referred to as the “mud line” throughout this document.
Therefore, there is a need for a device or apparatus that will allow wooden piles to be removed underwater, wherein such piles are removed beneath the mud line. Such a device that could remove piles without a significant increase in water turbidity and without necessitating the removal of mud or silt would be a substantial improvement over the prior art.